1. Field of the Invention
The present invention relates generally to solar water heating devices and, in one particular embodiment, to a metal water container, which extends through an opening in otherwise surrounding multiple glass tubes, which may comprise a twin glass vacuum tube.
2. Description of the Prior Art
Hot water represents the second largest energy consumer in American households. By heating household water with solar energy, 40%-70% of a family's water heating bill can be eliminated. The US Department of Energy reports that replacing one electric water heater with solar water heater can offset the equivalent of 40%-100% of the carbon dioxide emissions of one modern car. The use of a solar water heater also reduces nitrous oxide, and sulfur dioxide emissions, which are components of smog.
Various previous solar water heaters, some of which are discussed below, have numerous problems, some of which are discussed below. In some solar water heaters that utilize tubes within rectangular housings for mounting lengthwise on a house, the disadvantages comprise high cost of manufacturing, heavy installation weight of the unit that increases the difficulty of installation, and significant heat loss from the insulated box. In some cases, heat loss during the night can be half of the heat gain during the sunshine daytime. As well, for those units installed on a roof of a house, the roof tends to accumulate significant debris from leaves and the like which become trapped around and on the unit, requiring a great deal of cleaning and maintenance. Systems can be difficult to drain, especially in cold weather, and may have a tendency to leak when under pressure.
Other solar water heaters use complicated heat exchanger pipes, which may be insulated, and a heat transfer media to flow outside of the heat exchanger pipe to other pipes. The disadvantages include the high cost of the whole system, the heat transfer complexity of the system, and overall reliability of the system. Other problems relate to draining and problems with sealing. The installation costs also tend to be relatively high due to the complexity of the system. The potential leaking problem of these units increases significant when the internal pressure increases.
Accordingly, many attempts have been utilized to solve the above discussed problems, some of which are related to the following patents:
U.S. Pat. No. 4,587,952 to Richardson, issued May 13, 1986, discloses a passive solar water heater comprising a collector enclosure having a transparent upper surface and a curved, reflective inner surface and end walls. A storage tank within the collector enclosure is positioned to be heated by the sun's rays both directly and reflected from the inner surface of the collector enclosure. The storage tank has a cylindrical wall and opposed end walls. A first pipe extends through and is attached to one end wall along the longitudinal axis of the storage tank and extends to a position adjacent the cylindrical wall, inside the storage tank. A second pipe extends through the other end wall, along the longitudinal axis of the storage tank, to a second position in the storage tank, also adjacent the cylindrical wall. The first and second positions are generally diametrically opposed to each other. The first and second pipes extend through the end walls of the collector enclosure to support the storage tank within the collector enclosure. The relative positions of the collector enclosure, the storage tank and mounting frame can be fixed as desired.
U.S. Pat. No. 4,147,155 to Krafft, issued Apr. 3, 1979, discloses a device for collecting solar heat energy in which a transparent glass or plastic member, preferably extruded, is provided with the body having upper and lower and peripheral walls with integral passages extending therethrough parallel and spaced from the top and bottom walls and through which fluid is passed. On opposite sides of the passages, dead gas spaces are formed in the body of the glass or plastic material for insulating purposes.
U.S. Pat. No. 4,520,795 to Parkyn, et al., issued Jun. 4, 1985, discloses an apparatus for integral collection and storage of solar thermal energy, that comprises a relatively large storage vessel having side and end walls that absorb solar energy in order to heat its contents; a translucent enclosure surrounding the large storage vessel, for suppression of convective heat losses; and structure on the vessel for the suppression of thermal radiation heat losses from said large storage vessel. The apparatus provides a ratio of thermal mass, as measured in BTU per degree Fahrenheit, to heat-loss coefficient, as measured in BTU per degree Fahrenheit per hour, exceeding 36 hours.
U.S. Pat. No. 4,133,298 to Hayama, issued Jan. 9, 1979, discloses a solar heat collecting apparatus comprising at least one heat collecting element with a cylindrical outer member in which at least its circumferential wall has permeability to solar radiant energy and the two end faces of the cylinder are closed. A cylindrical inner member is disposed in the outer member with the interposition of a thermal insulating space with its either end protruding beyond each end face of the outer member. An absorbing means absorbs the difference between the amounts of heat expansion and contraction of the outer and inner members. The two members and the absorbing means are integrally formed.
U.S. Pat. No. 4,170,983 to Sadler, issued Oct. 16, 1979, discloses a novel solar collector comprising a base and a plurality of upstanding walls extending about the perimeter of the base. An input and an output extend through the walls to communicate with a plurality of liquid conduits integral with the base. A transparent cover is secured to the upstanding walls for covering the base and the plurality of conduits. The conduits and the base with the upstanding walls are constructed of a one-piece molding of a curable material.
U.S. Pat. No. 4,505,263 to Nameda, et al., issued Mar. 19, 1985, discloses a heat collector for a solar heat utilization system comprising a heat collecting pipe and a reflecting plate for focusing solar light on the pipe. This pipe has a first tubular portion for receiving solar light collected by the reflecting plate, and a second tubular portion for receiving direct solar light. The second portion has thermal expansion coefficient larger by a predetermined amount than that of the first portion, and thermally expands at the same rate as the first portion.
U.S. Pat. No. 4,579,107 to Deakin, issued Apr. 1, 1986, discloses a method and device manufactured thereby for economically making solar collectors and concentrators by employing a technique of applying high-efficiency, energy absorptive coatings. The technique is spraying less-than-ultra-pure nickel or chromium, in a molten state, onto a heated surface of a glass absorber substrate so that a thin metallic layer fuses thereon. After spraying, the metallic layer is chemically blackened. An outer glass insulator jacket is hermetically sealed, using a glass-to-glass junction, over the inner glass absorber substrate to provide an insulating space. The spraying technique employed is more economical than by applying the metallic coating by conventional vapor deposition and sputtering techniques which require expensive equipment and ultra-pure metals. Absorption efficiency exceeding 95% with infrared emissions below 0.09% has been achieved. Borosilicate glass is preferred, but other transparent substances can also be used. The technique is employed with both tubular and flat plate type solar collectors and/or concentrators.
U.S. Pat. No. 4,987,883 to Watkins, et al., issued Jan. 29, 1991, discloses an evacuated solar collector tube that has two tubes arranged concentrically and separated by a vacuum. The internal tube is of thin wall steel construction with a selective absorbing coating. The external tube is a hard glass material such as, for example, Pyrex. The vacuum tight seal between the concentric tubes consists of an accordion-pleated semi-rigid material such as copper connected to the inner tube. The semi-rigid material is then fused to a thermally insulating, vacuum tight spacer. Finally, the spacer is fused to the outer glass tube. Additional shatter protection may be derived from a reflective coating extending from midway along the ceramic spacer over the ceramic-glass seal, and along the glass for several inches.
U.S. Pat. No. 5,555,878 to Sparkman, issued Sep. 17, 1996, discloses a solar energy collector comprising a heat absorber to take in radiant energy and transfer the radiant energy to a heat transfer fluid carried thereby. A transparent jacket receives the heat absorber therein. The jacket will allow the radiant energy to pass therethrough and reach the heat absorber. Components are for hermetically sealing the jacket and to form a chamber about the heat absorber. A facility allows the heat transfer fluid to enter and exit from the heat absorber. A structure is provided for exhausting air out of the chamber, so as to produce a vacuum between the jacket and the heat absorber and to insulate the heat absorber from an external environment.
U.S. Pat. No. 4,674,478 to Liebard, issued Jun. 23, 1987, discloses a solar water heater for heating and storing water rough direct passage. The water heater includes a tank which mounted inside an outer structure inside of which is a high vacuum. Pipes acting as elastic water ducts seal water input and outputs which cross the outer glass structure. Recesses with spacers immobilize the tank inside the structure.
U.S. Pat. No. 7,220,365 to Qu, et al., issued May 22, 2007, discloses devices using a medium having a high heat transfer rate. Further disclosed are a heat transfer surface and a heat transfer element utilizing the heat transfer medium. Further disclosed are applications of the heat transfer element.
U.S. Pat. No. 7,431,030 to Nocera, issued Oct. 7, 2008, discloses a solar panel for a water-heater of the type comprising a heat exchanger made of molded synthetic material, having a plurality of passages in which a heat-exchanging fluid can circulate and a translucent cover sheet attached to the exchanger with a clearance, characterized in that the heat exchanger constitutes the brace supporting the panel and consists of two identical half-shells furnished with parallel longitudinal central projecting ribs and one projecting edging rib of greater dimension than a central rib, the two half-shells being bonded or heat sealed so that the central ribs define the abovementioned passages and that the respective edging ribs define a sealed hollow edging frame full of insulating air confined on the periphery of the exchanger.
U.S. Pat. No. 7,398,779 to Bowen, et al., issued Jul. 15, 2008, discloses a thermosiphon solar heater. The thermosiphon solar heater includes a substantially planar collector including a plurality of heat exchanger channels that are positioned next to one another in a parallel relationship. The thermosiphoning solar heater also includes a pair of headers fluidly coupled to the collector. A first header is disposed at a top end of the collector. A second header is disposed at a bottom end of the collector. The thermosiphoning solar heater further includes one or more exposed storage tanks fluidly coupled to the header and positioned in a side by side relationship next to the collector.
U.S. Pat. No. H2,231 to Teoh, published Aug. 4, 2009, discloses a collector core for a solar water-heating-system that includes a plurality of heat-absorbing pipes each of which surrounds a cooler-water return-pipe. The heating-pipes may connect directly to an insulated hot-water storage-tank from which cooler water descends through the return-pipes into the heating-pipes. Upon reaching the end of the return-pipes, the cooler water flows outward into the space between the surrounding heating-pipes and the inner return-pipes. Upon warming, water between the two pipes rises upward back to the hot-water storage-tank thus completing the thermosyphon flow cycle. Preferably, the inner return-pipe is made of polyvinyl chloride (“PVC”), polybutelene (“PB”), or other compressible material which permits collector core operation both in freezing and non-freezing environments. Alternatively, the collector core may be added to an existing solar water-heating panel to improve its operation.
U.S. Pat. No. 6,619,283 to Ghela, issued Sep. 16, 2003, discloses a solar collector pipe that directly conveys fluid to be heated and collects and transfers solar energy to the internal fluid. The solar collector pipe includes a transparent portion for admitting solar energy into the solar collector pipe. Internal to the solar collector pipe is an absorbing portion for absorbing solar energy. A conduit portion is also included and comprises a reflecting surface thereon for reflecting solar energy received through the transparent portion onto the absorbing portion. The transparent portion, the conduit portion, and the absorbing portion together define at least one fluid passageway for conveying the fluid. An internal conduit defines a fluid passageway for conveying the fluid. The internal conduit may be supported within the solar collector pipe and supported by heat-absorbing portions, or may be placed between two solar collector pipe sections to form a single solar collector pipe with an internal conduit extending therethrough.
U.S. Pat. No. 6,604,521 to Smith, et al., issued Aug. 12, 2003, discloses a solar collector pipe that conveys fluid to be heated and collects and transfers solar energy to the internal fluid, thereby maximizing both the amount of energy transmitted to the internal fluid and the peak temperature attainable by that fluid. The solar collector pipe includes a transparent portion for admitting solar energy into the solar collector pipe. Internal to the solar collector pipe is an absorbing portion for absorbing solar energy. A conduit portion is also included and comprises a reflecting surface thereon for reflecting solar energy received through the transparent portion onto the absorbing portion. The transparent portion, the conduit portion, and the absorbing portion together define at least one fluid passageway for conveying the fluid.
U.S. Pat. No. 6,769,427 to Mourani, issued Aug. 3, 2004, discloses a solar water heater comprising a water tank, a solar heating compartment for heating water, and an air pump. The water tank and the solar heating compartment are both substantially cylindrical, and the bottom surface of the heating compartment overlaps the top surface of the water tank. The solar heating compartment has an upper surface and a side surface which are substantially constructed from transparent materials. The heating compartment contains water tubing in communication with water in the water tank and at least one stainless steel parabolic reflector positioned for reflecting incident sunlight upon the water tubing for absorption. The water tubing terminates in at least one hot water outlet. The air pump is in communication with the water tubing within the solar heating compartment. Operation of the air pump causes a stream of water to continuously flow from the water tank to the hot water outlets by the siphoning effect.
U.S. Pat. No. 6,763,826 to Gumm, et al., issued Jul. 20, 2004, discloses a solar water heater. The heater features heat control so that a maximum temperature is automatically controlled. The heater is insulated to maintain a water temperature of water stored therein for long periods of time. The heater includes an insulated lens which transmits most solar radiation incident on its top surface through the lens. An air trap is located below the lens. A heat control valve opens the air trap to surrounding air when a maximum temperature for air within the air trap is exceeded. A heat absorption plate is located below the air trap. The plate is in contact with a heat transfer liquid within a liquid space below the plate. A heat exchanger is positioned within the space and routes water in heat transfer contact with the liquid within the space, while keeping the water isolated from the liquid within the space.
U.S. Pat. No. 6,679,247 to Gozikowski, issued Jan. 20, 2004, discloses a solar water heaters with a solar collector in a decorative structure, and solar collectors comprising a coil of tubing adapted to be disposed in a decorative structure such as a wishing well. A solar water heating system comprises a decorative structure and a coil of tubing disposed within the decorative structure, the coil having a helical shape and being oriented with its axis disposed generally vertically. A method comprises the steps of providing a coil of tubing, the coil having an axis and the tubing of the coil being radially spaced from the axis; disposing the coil in a location receiving sunlight with the coil axis oriented generally vertically; and causing fluid to flow through the coil. A method of making a solar collector for a solar water heating system comprises the steps of providing a supply of flexible tubing and a frame; securing a portion of the tubing to the frame; and rotating the tubing supply and the frame relative to one another so as to dispose a portion of the tubing in successive turns around the frame to form a coil.
U.S. Pat. No. 6,119,682 to Hazan, issued Sep. 19, 2000, discloses a solar energy powered, thermosyphon-circulated water heater and storage device comprising: a flat, tilted solar radiation absorber panel; an insulated hot fluid storage tank; a conduit providing fluid communication between a lower area of the absorber panel and the storage tank, and a further conduit providing fluid communication between an upper area of the absorber panel and an upper area of the storage tank to complete a thermosyphonic path between the panel sand the tank. An extended-length heat-exchanger piping circuit has an entry port for cold, line-pressure water, an outlet port for hot water and arranged within the tank to facilitate the transfer of heat between fluid held in the storage tank and line-pressure water passing through the piping; and, an electric water immersion heater positioned in a housing located in an upper area of the storage tank adjacent the extended length piping circuit.
U.S. Pat. No. 5,823,177 to Whitehead, issued Oct. 20, 1998, discloses a pumpless solar water heater with isolated pressurized storage including a variable volume of solar heated water stored in an insulated indoor tank. The hot water is indirectly pressurized by incoming cold water, which is accumulated separately to maintain a constant total volume without mixing. A small reduction in the total pressure of hot water is maintained, so that water can flow through a solar heat collector and into hot storage without pumps. In one preferred embodiment, the incoming cold water is accumulated in a tank located above an insulated hot water tank. The tanks share a volume of compressed air, which freely passes through a pipe connected between the tops of the two tanks. The transfer of compressed air permits incoming cold water to pressurize and displace hot water without mixing or heat loss. A control valve is opened during sunny hours to permit flow from the upper tank, through a solar heat receiver, and into the lower tank. This collector flow is driven by the reduced elevation pressure of water in the lower tank, so no pump is needed. The air pipe additionally serves as a bypass to deliver cold water after all hot water is used. Means are provided for freeze protection, replacement of lost air, and venting of excess air. The collector may be located on the roof of a building, while the tanks are located lower in the building.
U.S. Pat. No. 5,806,511 to Hart, issued Sep. 15, 1998, discloses a method and apparatus to prevent freezing in the piping and tank of a solar water heating system mounted above a heated space. The supply and return piping to the solar water heater is used in conjunction with a heat exchanger mounted within the heated space below, to create a mechanism for the gentle circulation of water by natural convection, sufficient to prevent freezing in the tank and piping. Bypass pipes that incorporate flow restrictions are introduced between the supply and return piping both in the building and just below the solar tank. This creates a loop in the piping which allows natural convection to occur. The flow restrictions are provided so as not to short circuit the normal water flow under conditions of hot water demand.
Chinese patent number 201037703Y, to Huang Yongsheng issued Mar. 19, 2008, discloses a solar water heater which comprises a glass vacuum tube with an end disposed in an end box, a sealing plug which goes into the open end of the vacuum tube, the sealing plug being attached to the anchor board with screw, and a number of vacuum tubes, which are connected in series by connecting hoses and pressure relief hoses. There is an overflow outlet on the top vacuum tube of the solar water heater. There is an outlet on the bottom vacuum tube of the solar water heater. The solar water heater has a large diameter vacuum tube as a storage tank. The solar water heater can be installed with different angles on the top of roof or vertically installed on the building wall.
Chinese patent number 201032302Y, to Duanquiao et al., issued Mar. 5, 2008, discloses a solar water heater which comprises two or more storage tanks. The storage tanks together with solar evacuated tubes, and other parts can form the solar water heater. One inlet and one outlet are disposed on the storage tanks. The outlet of a previous storage tank is connected to the inlet of the next storage tank. The storage tanks are connected in series.
The above cited prior art does not disclose suitable solutions to the above discussed problems. Consequently, those skilled in the art will appreciate the present invention that addresses the above and other problems.